Island



0. D. ROGERS. DIE FOR MAKING ROLLED WOOD SCREWS;- No. 440,332.

(No Model.)

Patented Nov. 11, 1890.

INVENTEIFM WITNESS E5- L3 jm UNITED STATES PATENT OFFICE.

CHARLES D. ROGERS, OF PROVIDENCE, RI-IODE ISLAND, ASSIGNOR TO THEAMERICAN SCREW COMPANY, OF SAME PLACE.

DIE FOR MAKING ROLLED WOOD-SCREWS.

SPECIFICATION forming part of Letters Patent No. 440,332, dated November11, 18$0. Application filed August 4, 1890, Serial No. 366,867. (Nomodel.)

To aZZ whont it may concern:

Be it known that I, CHARLES D.RoGERs, a citizen of the United States,residing at Providence, in the county of Providence and State of RhodeIsland, have invented certain new and useful Improvements in Dies forRolling Gimlet-Pointed Wood-Screws; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,and to the letters of reference marked thereon, which form a part ofthis specification.

Dies of the class forming the subject of the improvement hereinafterdescribed and claimed have been employed before in the manufacture ofrolled thread wood-screws; but the particular type of screw to which mypresent improved die relates is that known as gimlet-pointedwood-screws.

Heretofore it has been the usual practice to provide the working-facesof thread-rolling dies with a series of inclined parallel ribs andgrooves, the form or contour of the die, transversely taken through itsface, being substantially alike throughout the length of the die; or, inother words, the ribs are so arranged that they produce the threads bothupon the cylindrical or shank portion and the point portionsimultaneously. An obj ection to the use of such former dies,irrespective of the shape of the ribs cross-sectionally, is that theportion of the dies adjacent to the point portion of the screw-blankwhen properly entered between them is beveled at an angle substantiallylike that of the blank. Such beveled portion extends throughout thelength of the die and is provided with threadforming ribs and grooves,which are a continuation of the ribs and grooves formed on the planeportions of the die, substantially as before stated. Now when dies thusmade are employed it is evident that the ribs are acting at once uponthe entire portion of the blanks surface,which is to be screw-threaded.Such simultaneous action renders it difiicult for the blank to maintainitself in a proper position or relation until the completion of thescrew-threads. It is, in fact, due to this cause alone that aconsiderable portion of the product is rendered imperfect or unsalable.Moreover, as a result of such former construction of dies itis clearlyapparent that the cone-shaped or point portion of the blank must slipmore or less upon the dies during its passage between them or whilebeing acted upon by them, even though the cylindrical portion of theblank doesnot slip at all dur- 6o ing the operation.

The object I have in view in the invention illustrated and describedherewith is to produce a die for rolling the threads of gimletpointedwood-screws, which is free from the objections or disadvantages beforereferred to as incident to the use of dies heretofore made.

To that end my invention consists, essentially, of a die having itslower or pointthreading portion cut away at the front end,

so as to not engage the cone-shaped point portion of the blank until theribs have commenced to act fairly upon the cylindrical part of theblank. The lower portion of the die from this point gradually increasesin height in a bevel form above the general surface, and is alsoprovided with thread-forming ribs and grooves communicating with thoseof the main portion of the die until at or nearly to the back end of thedie the raised bevel-shaped portion has a form transversely thecounterpart of that to be given to the threaded screw-point. By means ofmy improved dies the screw-thread is gradually produced upon the pointportion, the same commencing at the base of the point and terminating ator near the end of the screw when the dies have nearly completed theirmovement. In view of the foregoing it is evi- 9o dent that the blank isto a great extent prevented from slipping.

In the accompanying drawings, Figure 1 represents a side or frontelevation of a thread-rolling die embodying my improvement, the samehaving its working-face provided with inclined ribs and grooves, andhaving the lower portion cut away and also provided with inclined ribsand grooves gradually increasing in length and communicat- 10o however,be advantageously used on curved dies.

r designates the ribs, and g the grooves formed between the ribs. I makeno claims herewith to any specific form of ribs and grooves, as they mayhave any suitable shape transversely if adapted to the work required ofthem. The ribs should presentas little surface or area as possible tothe screw-blank, so that they can be the more readily impressed into themetal. The form of the ribs and grooves should change so that at theopposite end of the die the grooves are the counterpart of thescrew-threads to be produced.

The major portion of the working-face of the die longitudinally is fiator substantially uniform in height throughout. The dotted line 7", Fig.2, indicates the face of the ribs of such portion, and g the bottom ofthe grooves. By referring to said Fig. 2 it will be seen that the diehas a wedge-shaped portion f along its edge, the same commencing at theright, or as drawn the entering end substantially flush with the ribs 0'or surface '1". From this pointit extends longitudinally of the die inan incline at until it reaches a point at near the opposite end, andfrom thence it extends, as at a, substantially parallel with but higherthan the line 1" to the end, the vertical distance I) (see also Fig. 5)

between these lines a and r being substantially equal to thesemidiameter of the screw at the core or bottom of the screw-thread. Theinclined flat surface or portion a could be removed up to the line h,Fig. 1, without materially affecting the manner of the action of the-dieupon the metal. Such'portion is left, however, because it is moreconvenient, and at the same time the die is rendered more symmetrical.

It will be seen by referring to Fig. 1 that the inclined or beveledpoint-threading portion 19 of the die extends rearwardly in agradually-increasing manner, as indicated by the inclined line 71,, theline 3 .9, parallel with the upper edge of the die, indicating theintersection of such portion with the main portion 1". By reason of thisconstruction the cone-shaped point of the screw-blank is graduallythreadcd, the several ribs of a pair of such dies successively actingupon said point until at the end of the operation the screw drops fromthem fully threaded.

I claim A die for forging the threads upon a screw by rolling, having atits entering end a plane surface only, provided with ribs to form thethreads on the cylindrical portion of the blank and toward the finishingend asurface inclined to the plane surface and corresponding to thesurface of the point of the screwblank provided with ribs which engagein succession with the metal to form the threads on the point.

In testimony whereof I have aflixed my signature in presence of twowitnesses.

CHARLES D. ROGERS.

Witnesses:

CHARLES HANNIGAN, GEO. H. REMINGTON.

